At the very least you will need a bi-metal hole saw of the right size for the hole and a decent speed control drill. When drilling stainless opt for a slow speed, no slower than that. Use some lube as well <!-- s:shock: --><img src="{SMILIES_PATH}/icon_eek.gif" alt=":shock:" title="Shocked" /><!-- s:shock: --> water or oil and take frequent breaks.
You don't want this to overheat, it will harden the steal and melt the drill bit.
Unless you have the equipment and the confidence to use it I suggest paying someone to do it for you.